Occupational health is of very serious concern in today's society and people are also becoming more aware of bodily health. To mitigate potential hearing damage in noisy environments, different forms of hearing protection are readily available. However using these hearing protection devices has a negative impact on people's ability to hear and so to communicate.
In addition to the sound source that is desired to be heard being the voice of a person, other environments or situations may require a person to hear a sound, other than a voice of a person, in environments where there is unwanted noise that interferes with this process. Similar considerations as discussed above apply in these situations as well. Thus, whilst in typical situations it is the voice of a person that is desired to be heard over other sounds in the environment, the sound desired to be heard may be other than a human voice.